1. Field of the Invention
The present invention relates to a design support technique for an image forming apparatus.
2. Description of the Related Art
Software controls mechanisms constituting an image forming apparatus. For example, when conveying a recording member by using a conveyance mechanism including rollers, guides, and the like, software detects the position of the recording member based on an output from a sensor, and controls the positioning of the recording member based on the detection result. In addition, software controls the switching of conveyance paths for the recording member by reversing rollers upon switching the direction of a flapper. It is necessary to change control on the switching timings of the stop position of a recording member and the direction of a flapper, the conveyance velocity of the recording member, and the like in accordance with the size or type of recording member. Control by software is indispensable to perform such complicated control.
With the recent tendency toward higher performance and productivity of image forming apparatuses, software for controlling such image forming apparatus has become more complicated. This increases the number of steps necessary to specify the cause of a problem after it is found in control and also increases the number of steps necessary to correct the software so as to solve the problem and to evaluate the correction result.
An improvement in the performance of a general-purpose computer has increased the chances of using a simulation technique for mechanism design for a conveyance mechanism and the like. For example, Japanese Patent Laid-Open No. 9-81600 has proposed a system for detecting a mechanical defect in a conveyance mechanism by calculating the behavior of a target conveyance member in a conveyance path by simulation.
Japanese Patent Laid-Open No. 5-143260 discloses an arrangement for generating external events, for example, switching on/off printer control software and opening/closing a cover from an input device such as a keyboard.
Although there are simulation systems for evaluation mechanisms, there are still not many design support techniques for inspecting software for controlling mechanisms.
FIG. 6 is a view for explaining conveyance control on a recording member in an image forming apparatus according to the prior art. First of all, this apparatus conveys a recording member P conveyed from the direction indicated by an arrow 611 to the direction indicated by an arrow 615 in FIG. 6 by using rollers 603 upon tilting a flapper 601 to the left (in the arrow 633 direction) in FIG. 6. When a sensor 602 detects that the trailing edge of the recording member P has passed through the branch point of the flapper 601, the apparatus temporarily stops the rotation of the rollers 603 and stops the conveyance of the recording member P. The apparatus then switches the direction of the flapper 601 to the right (the arrow 634 direction) in FIG. 6, and reverses the rotating directions of the rollers 603, thereby performing control to feed the recording member P in the direction indicated by an arrow 612. Switching the operations of the rollers 603 and flapper 601 at predetermined timings in this manner will switch the conveyance direction of the recording member P, thereby performing recording member reversing control at the time of double-sided printing.
It should be noted in this case that when, for example, the motor which drives the rollers 603 is a stepping motor, there is a limitation that the motor must be stopped for a predetermined period of time at the time of switching of the rotating direction of the motor in order to prevent step-out.
Alternatively, depending on the switching mechanism for the flapper 601, there is a predetermined time lag between the instant the apparatus controls a clutch and the like for switching the direction of the flapper and the instant the direction of the flapper 601 is reliably switched in fact. In this case, control needs to be performed in consideration of the time lag because the switching operation of the flapper 601 must be complete before the leading edge of the recording member P reaches the flapper 601.
Conventionally, in an operation inspection environment using an actual apparatus, a jam occurs when the motor causes step-out due to a control error by software or the recording member P is fed into a false path due to a switching error on the flapper. In order to continue operation inspection, the user must actually remove the jammed recording member. In this case, the actual apparatus fails, and the operation inspection is forced to be interrupted. In this regard, operation inspection using an actual apparatus is inefficient.
Assume that software has caused a control error. In this case, if this error is not fatal and conveyance control can be performed on a recording member, it is difficult to extract a problem in the software. Even if a software problem has become obvious afterward, it requires many steps to pursue the cause of the problem and correct the software.
The technique disclosed in Japanese Patent Laid-Open No. 9-81600 can specify the cause of a potential problem in hardware, but cannot specify the cause of a potential problem in software which controls the hardware.
Furthermore, the technique disclosed in Japanese Patent Laid-Open No. 5-143260 can find a potential problem in software, but cannot specify the cause of the problem.